College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

Exercise 76

(a) We commonly say that friction opposes motion. Yet when we walk, the frictional force is in the direction of our motion (Fig. 4.17). Is there an inconsistency in terms of Newton's second law Explain. (b) What effects would wind have on air resistance [ Hint : The wind can blow in different directions.]